This invention relates to sorping particles and particular agglomerated cellulosic particles which have various industrial and household uses such as for the sorption of oil, grease and the like from floors and elsewhere where such materials represent a safety hazard. In addition, because of their water sorbing and deodorizing characteristics, the particles have been found particularly useful as litter or bedding for animals. More particularly, although not exclusively, it may be adapted to a litter for domestic pets such as cats, dogs, mice, rats, gerbils and the like. The invention also relates to a bed of such particles.
Commercially available cat litters frequently contain clay. Clay litters are a disadvantage since they are heavy, dusty, and stick together to form clumps in the bottom of the litter box after use. In addition, because clay litters have low absorbency, cat urine tends to pool on the bottom of the litter box and creates an odor problem as bacterial growth increases.
In an attempt to overcome the disadvantages of clay litters, other commercially available cat litters have been made from cellulosic materials such as newsprint and alfalfa. These products contain water-soluble binders and are produced by extrusion and pelletization of the extrudate. However, such products also suffer certain disadvantages. In particular, during use the pellets swell and break apart, resulting in a mess in the litter box. Also, these products are dusty in spite of the presence of binders because the exposed ends of the pellets are subject to attrition during shipment and use.
U.S. Pat. No. 3,789,797 discloses an animal litter which is prepared by mixing ground alfalfa screened through a 50 mesh screen with 2 to 50 percent by weight bentonite. The resulting mixture is mixed with a binder such as molasses, wood molasses, modified starches or a non-toxic glue and then pelletized and dried. The pellets contain chlorophyll which is disclosed as an effective odor control of animal waste and the particle mixture is disclosed as not readily tracked from the litter area by the animal. The moisture level of the mixture before pelletizing is about 5 to 60 percent. The pellets are tumbled to gradually be enlarged by snowballing to the desired size but the pellet is not compacted. The final pellet contains about 5 to 8 percent moisture. The dried pellets are then screened to remove large particles and fines from the pellets. However, the fines are present in the final product since particles tend to disintegrate during normal shipment.
U.S. Pat. No. 3,256,857 discloses an animal bedding material comprising wood particles of substantially uniform shape and size, the size being generally 1/10" by 1/10", preferably 1/20" by 3/10" and adapted to be sifted through a size 8 mesh screen and retained by a size 16 mesh screen.
U.S. Pat. No. 3,828,731 discloses an animal litter comprising pieces and shavings of substantially pure organic cellulosic material having a high inherent characteristic for liquid absorption and including at least one microbial inhibitor. The cellulosic material is further described as including alpha cellulose, sulphite cellulose. The inhibitor is described as including benzaldehyde green, rose bengal, sodium propionate, calcium propionate, quaternary ammonium compounds, and combinations thereof. The litter could also include a surface active agent from selected cationic, anionic or nonionic surface active agent groups.
U.S. Pat. No. 4,459,368 discloses a sorbing and deodorizing composition comprising particulate mixtures of articulate synthetic and clay particle sorbents. The size of the clay particles was considered significant and preferred to be such that no more than about 60 weight percent passed through a 2 mesh sieve screen and was retained on a 6 mesh sieve screen. The clays were disclosed to sorb an amount of more than 50 weight percent of the particle.
U.S. Pat. No. 4,459,368, however, indicates that fines should be preferably present; more preferably at least 1 percent by weight of the particles should pass a 40 mesh sieve screen; and most preferably at least 3 to 5 percent of the composition should pass through a 40 mesh sieve screen.
U.S. Pat. No. 4,203,388 discloses an animal litter comprising pelletized and dried cellulose containing rejects, mineral fillers, suitable deodorant materials, such as sodium bicarbonate, chlorophyll, and sodium dehydrogen phosphate in amounts ranging from 1 to 10 percent. The litter could also include bactericides.
U.S. Pat. No. 4,305,345 discloses manufacture of litter particles by adding hot water and aluminum silicate or calcium carbonate (feldspar) to a paper pulp to form a slurry, dehydrating the slurry, forming pulp lumps, rolling the lumps, dehydrating to between 28 and 45 percent solids, rotating the particles and drying the solids to 90 percent solids. The patent discloses as an object the manufacture of platelet-like particles but does not teach such manufacture. The feldspar is added to effect non-sticking behavior of the particles.
U.S. Pat. No. 4,187,803 discloses a process for pelletizing sorptive mineral fines which includes adding sufficient moisture to the particles to occupy the pore space, compactly forming the moistened mineral in pellet form, and then drying the compacted pellets to retain the same absorbent capacity and bulk density as the original material. The sorptive minerals were defined as clays, diatomaceous earth, fuller's earth and bentonite. The patent recognizes the fines which pass through a 20 mesh screen are not satisfactory for a commercial product.
U.S. Pat. No. 3,675,625 discloses an animal litter which produces a fragrant odor when contacted with an aqueous liquid which comprises a high density absorbent with a moisture content of less than 12 percent and a highly polar fragrant odor control agent. The odor control agent comprises about 0/1 to 1 percent of the litter weight. The litter has a particle size capable of passing through a No. 6 Tyler screen and is substantially retained by a No. 35 Tyler screen.
U.S. Pat. No. 3,415,397 discloses a litter material having a particle size ranging from 4 to 20 mesh and having a density of about 3 pounds per 51/2 quarts. The litter material consisted of alfalfa, algae, broome grass and timothy grass and a lightweight absorbent of either vermiculite or perlite.
U.S. Pat. No. 3,059,615 discloses treatment of a cellulosic material with a controlled amount of acid to bring the pH of the material to between 2.5 and 3.5. Suitable acids include mineral acids, phosphoric acids and citric acid.
European Application No. 812000142, Publication No. 0039 522 A2 discloses a cellulose/filter material useful for liquid absorbing and shock absorbing which has a dry bulk density not more than 400 kg/m.sup.3 and a water content of 0.5 to 10 percent by weight. Preferably the water content is between 5 and 8 percent by weight. The pellets are capable of absorbing 80 to 150 percent of their own weight in oil or 200-300 percent of their own weight in water.
Therefore, it is an object of this invention to provide a particle, especially useful as an animal litter, which is light, substantially dust-free, attrition resistant, bed stable, resistant to flow, absorbent, easy to clean up, and which wicks away free liquid to avoid liquid pooling which in turn mitigates bacterial growth. It is a further object of this invention to provide a particle having other uses such as a floor sweeping material, an oil absorbent, a packing material, a mulch, or a carrier for other materials such as scents, disinfectants, germicides, or the like.